Ansible module “apt” always return “changed: true” in Debian

Ansible module “apt” always return “changed: true” in Debian, when you try to install:

php5-json

because:

$ sudo apt-get install php5-json
Reading package lists… Done
Building dependency tree
Reading state information… Done
Note, selecting ‘php5-common’ instead of ‘php5-json’
php5-common is already the newest version.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.